Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-9 (of 9 Records) |
Query Trace: Mei JV[original query] |
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Performance of laboratory tests used to measure blood phenylalanine for the monitoring of patients with Phenylketonuria
Moat SJ , Schulenburg-Brand D , Lemonde H , Bonham JR , Weykamp CW , Mei JV , Shortland GS , Carling RS . J Inherit Metab Dis 2019 43 (2) 179-188 Analysis of blood phenylalanine is central to the monitoring of patients with phenylketonuria (PKU) and age-related phenylalanine target treatment-ranges (0-12 years; 120-360 mumol/L, and > 12 years; 120-600 mumol/L) are recommended in order to prevent adverse neurological outcomes. These target treatment-ranges are based upon plasma phenylalanine concentrations. However, patients are routinely monitored using dried bloodspot (DBS) specimens due to the convenience of collection. Significant differences exist between phenylalanine concentrations in plasma and DBS, with phenylalanine concentrations in DBS specimens analysed by flow-injection analysis tandem mass spectrometry (FIA-MS/MS) reported to be 18-28% lower than paired plasma concentrations analysed using ion-exchange chromatography (IEC). DBS specimens with phenylalanine concentrations of 360 mumol/L and 600 mumol/L, at the critical upper-target treatment-range thresholds would be plasma equivalents of 461 mumol/L and 768 mumol/L respectively, when a reported difference of 28% is taken into account. Furthermore, analytical test imprecision and bias in conjunction with pre-analytical factors such as volume and quality of blood applied to filter paper collection devices to produce DBS specimens affect the final test results. Reporting of inaccurate patient results when comparing DBS results to target treatment-ranges based on plasma concentrations, together with inter-laboratory imprecision could have a significant impact on patient management resulting in inappropriate dietary change and potentially adverse patient outcomes. This review is intended to provide perspective on the issues related to the measurement of phenylalanine in blood specimens and to provide direction for the future needs of PKU patients to ensure reliable monitoring of metabolic control using the target treatment-ranges. This article is protected by copyright. All rights reserved. |
The Newborn Screening Quality Assurance Program at the Centers for Disease Control and Prevention: thirty-five year experience assuring newborn screening laboratory quality
De Jesus VR , Mei JV , Cordovado SK , Cuthbert CD . Int J Neonatal Screen 2015 1 (1) 13-26 Newborn screening is the largest genetic testing effort in the United States and is considered one of the ten great public health achievements during the first 10 years of the 21st century. For over 35 years, the Newborn Screening Quality Assurance Program (NSQAP) at the US Centers for Disease Control and Prevention has helped NBS laboratories ensure that their testing does not delay diagnosis, minimizes false-positive reports, and sustains high-quality testing performance. It is a multi-component program that provides comprehensive quality assurance services for dried blood spot testing. The NSQAP, the Biochemical Mass Spectrometry Laboratory (BMSL), the Molecular Quality Improvement Program (MQIP) and the Newborn Screening Translation Research Initiative (NSTRI), aid screening laboratories achieve technical proficiency and maintain confidence in their performance while processing large volumes of specimens daily. The accuracy of screening tests could be the difference between life and death for many babies; in other instances, identifying newborns with a disorder means that they can be treated and thus avoid life-long disability or severe cognitive impairment. Thousands of newborns and their families have benefited from reliable and accurate testing that has been accomplished by a network of screening laboratories and the NSQAP, BMSL, MQIP and NSTRI. |
A pilot study using residual newborn dried blood spots to assess the potential role of cytomegalovirus and toxoplasma gondii in the etiology of congenital hydrocephalus
Simeone RM , Rasmussen SA , Mei JV , Dollard SC , Frias JL , Shaw GM , Canfield MA , Meyer RE , Jones JL , Lorey F , Honein MA . Birth Defects Res A Clin Mol Teratol 2013 97 (7) 431-6 BACKGROUND: Congenital hydrocephalus is a condition characterized by accumulation of cerebrospinal fluid in the ventricles of the brain. Prenatal infections are risk factors for some birth defects. This pilot study investigated whether residual dried blood spots (DBS) could be used to assess infections as risk factors for birth defects by examining the associations between prenatal infection with Toxoplasma gondii (T. gondii) or cytomegalovirus (CMV) with congenital hydrocephalus. METHODS: Case-infants with hydrocephalus (N = 410) were identified among live-born infants using birth defects surveillance systems in California, North Carolina, and Texas. Control-infants without birth defects were randomly selected from the same geographic areas and time periods as case-infants (N = 448). We tested residual DBS from case- and control-infants for T. gondii immunoglobulin M and CMV DNA. When possible, we calculated crude odds ratios (cORs) and confidence intervals (CIs). RESULTS: Evidence for prenatal T. gondii infection was more common among case-infants (1.2%) than control-infants (0%; p = 0.11), and evidence for prenatal CMV infection was higher among case-infants (1.5%) than control-infants (0.7%; cOR: 2.3; 95% CI: 0.48, 13.99). CONCLUSIONS: Prenatal infections with T. gondii and CMV occurred more often among infants with congenital hydrocephalus than control-infants, although differences were not statistically significant. This pilot study highlighted some challenges in using DBS to examine associations between certain infections and birth defects, particularly related to reduced sensitivity and specimen storage conditions. Further study with increased numbers of specimens and higher quality specimens should be considered to understand better the contribution of these infections to the occurrence of congenital hydrocephalus. (Birth Defects Research (Part A), 2013. (c) 2013 Wiley Periodicals, Inc.) |
Quantitative assessment of anthrax vaccine immunogenicity using the dried blood spot matrix
Schiffer JM , Maniatis P , Garza I , Steward-Clark E , Korman LT , Pittman PR , Mei JV , Quinn CP . Biologicals 2012 41 (2) 98-103 The collection, processing and transportation to a testing laboratory of large numbers of clinical samples during an emergency response situation present significant cost and logistical issues. Blood and serum are common clinical samples for diagnosis of disease. Serum preparation requires significant on-site equipment and facilities for immediate processing and cold storage, and significant costs for cold-chain transport to testing facilities. The dried blood spot (DBS) matrix offers an alternative to serum for rapid and efficient sample collection with fewer on-site equipment requirements and considerably lower storage and transport costs. We have developed and validated assay methods for using DBS in the quantitative anti-protective antigen IgG enzyme-linked immunosorbent assay (ELISA), one of the primary assays for assessing immunogenicity of anthrax vaccine and for confirmatory diagnosis of Bacillus anthracis infection in humans. We have also developed and validated high-throughput data analysis software to facilitate data handling for large clinical trials and emergency response. |
Proficiency testing outcomes of 3-hydroxyisovalerylcarnitine measurements by tandem mass spectrometry in newborn screening
Lim TH , De Jesus VR , Meredith NK , Sternberg MR , Chace DH , Mei JV , Hannon WH . Clin Chim Acta 2010 412 631-5 BACKGROUND: The use of tandem mass spectrometry (MS/MS) for the analysis of amino acids and acylcarnitines from dried-blood spots (DBS) has become routine practice in newborn screening laboratories. The Newborn Screening Quality Assurance Program (NSQAP) added 3-hydroxyisovalerylcarnitine (C5OH) into its routine quality control and proficiency testing (PT) DBS materials for MS/MS to assure the quality of C5OH screening. We report the results from NSQAP evaluations for C5OH-enriched DBS, and summarize participant screening practices based on their analytical methods. METHODS: NSQAP prepared C5OH-enriched DBS materials for its participants. Laboratories reported quantitative and qualitative results. Bias plots of quantitative results were constructed using reported data and the results were sorted by analytical method. RESULTS: NSQAP participants reported PT specimen 3964 as outside of normal limits for C5OH. The mean C5OH value for derivatized and non-derivatized methods was 2.80 and 2.67mumol/l, respectively. Reported data from other specimens showed a similar trend in derivatized vs. non-derivatized assay results. Differences in C5OH quantitative values were observed among laboratories using different internal standards. CONCLUSIONS: C5OH MS/MS measurements in DBS assays varied by method and the choice of internal standards. The use of NSQAP's DBS materials allows harmonization of C5OH measurements by newborn screening laboratories worldwide. |
Effect of specimen storage conditions on newborn dried blood spots used to assess Toxoplasma gondii Immunoglobulin M (IgM)
Mei JV , Li L , Rasmussen SA , Collier S , Frias JL , Honein MA , Shaw GM , Lorey F , Meyer R , Chaing S , Canfield MA , Jones J , Hannon WH . Clin Chim Acta 2010 412 455-9 BACKGROUND: Newborn screening programs store-under varying conditions-residual dried blood spots (DBS). Residual DBS were used to investigate the contribution of congenital infection with Toxoplasma gondii to the etiology of hydrocephalus and as a key step, we assessed the effect of storage conditions on the stability of newborn screening biomarkers. METHODS: Infants with hydrocephalus (410 cases) were identified using population-based birth defects surveillance systems in California, North Carolina, and Texas. Infants without birth defects (448 controls) were randomly selected from the same geographic areas and time periods. California stores DBS with controlled temperature, while North Carolina and Texas store DBS under ambient conditions. After removal of personal identifiers, DBS were tested for Toxo-specific immunoglobulin-M (Toxo-IgM). Because of poor elution of DBS stored in ambient conditions, additional biomarkers were tested on a specimen subset. RESULTS: Among 858 DBS tested, Toxo-IgM was found in 3 cases and no controls from California (N=515) and in no specimens from North Carolina or Texas (N=343). Among the 98 specimens tested for selected biomarkers, statistically significant differences were found for California vs. combined North Carolina and Texas DBS (thyroid stimulating hormone, phenylalanine, methionine, leucine, citrulline p<0.0001; tyrosine, valine p<0.001). CONCLUSIONS: Storage conditions for residual DBS had an effect on the ability to extract, recover, and accurately measure Toxo-IgM and other biomarkers from the filter paper matrix. |
Pilot proficiency testing study for second tier congenital adrenal hyperplasia newborn screening
De Jesus VR , Simms DA , Schiffer J , Kennedy M , Mei JV , Hannon WH . Clin Chim Acta 2010 411 1684-7 BACKGROUND: Congenital adrenal hyperplasia (CAH) is caused by inherited defects in steroid biosynthesis. The Newborn Screening Quality Assurance Program (NSQAP) initiated a pilot, dried blood spot (DBS)-based proficiency testing program designed to investigate materials and laboratory performance for second tier CAH screening by tandem mass spectrometry (MS/MS). METHODS: The ratio of 17-alpha-hydroxyprogesterone (17-OHP), androstenedione (4-AD) and cortisol is used as an indicator of CAH in laboratory protocols for second tier analysis of DBS specimens. DBS prepared by NSQAP contained a range of steroid concentrations resulting in different clinical ratios. Laboratories received blind-coded DBS specimens and reported results to NSQAP for evaluation. RESULTS: Quantitative values reported by participants for 17-OHP, 4-AD, cortisol, reflected small differences in their analytical methods. Average quantitative values for 17-OHP increased from 81% to 107% recovery over the 3.5-y period; cortisol recoveries increased from 61.9% to 89.5%, and 4-AD recoveries decreased from 184% to 68%. CONCLUSIONS: Laboratory participation in the CAH second tier proficiency testing program has resulted in improved analyte recoveries and enhanced sample preparation methodologies. NSQAP services for the second tier CAH analysis in DBS demonstrate the need for surveillance to ensure harmonization and continuous improvements, and to achieve sustained high-performance of newborn screening laboratories worldwide. |
Improving and assuring newborn screening laboratory quality worldwide: 30-year experience at the Centers for Disease Control and Prevention
De Jesus VR , Mei JV , Bell CJ , Hannon WH . Semin Perinatol 2010 34 (2) 125-33 Newborn screening is the largest population-based genetic screening effort in the United States. The detection of treatable, inherited congenital disorders is a major public health responsibility. The Centers for Disease Control and Prevention's (CDC's) Newborn Screening Quality Assurance Program helps newborn screening laboratories ensure that testing accurately detects these disorders, does not delay diagnosis, minimizes false-positive reports, and sustains high-quality performance. For over 30 years, the CDC's Newborn Screening Quality Assurance Program has performed this essential public health service, ensuring the quality and accuracy of screening tests for more than 4 million infants born each year in the United States and millions more worldwide. The Program has grown from 1 disorder in 1978 for 31 participants to more than 50 disorders for 459 participants in 2009. This report reviews the Program's milestones and services to the newborn screening community. |
Comparison of amino acids and acylcarnitines assay methods used in newborn screening assays by tandem mass spectrometry
De Jesus VR , Chace DH , Lim TH , Mei JV , Hannon WH . Clin Chim Acta 2010 411 684-9 BACKGROUND: The analysis of amino acids (AA) and acylcarnitines (AC) by tandem mass spectrometry (MS/MS) is performed in newborn screening laboratories worldwide. While butyl esterification assays are routine, it is possible to detect AAs and ACs as their native free acids (underivatized). The Centers for Disease Control and Prevention's Newborn Screening Quality Assurance Program provides dried-blood spot (DBS) quality control (QC) and proficiency testing (PT) programs for numerous MS/MS analytes. We describe empirical differences between derivatization and non-derivatization techniques for selected AAs and ACs. METHODS: DBS materials were prepared at levels near, above and below mean domestic laboratory cut-offs, and distributed to program participants for MS/MS analysis. Laboratories reported quantitative and qualitative results. QC DBS materials were assayed in-house following established protocols. RESULT: Minor differences (<15%) between quantitative values resulting from butyl esters and free acid techniques were observed for the majority of the analytes. Mass spectrometric response from underivatized dicarboxylic acid acylcarnitines was less intense than their butyl esters. CONCLUSIONS: The use of underivatized techniques may also result in the inability to differentiate isobaric acylcarnitines. Laboratories should establish their own protocols by focusing on the decisions that identify test results requiring additional follow-up testing versus those that do not. |
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